Archery bows are available in a variety of forms and may comprise a vast range of designs and functions. Examples of bow designs include, but are not limited to, long bows, recurve bows, compound bows, and so forth. Bows have in common the fact that they are all basically intended to propel an arrow through the flexure of limbs that transfer stored energy through such flexure to the arrow through the bow string.
Many of the bow types including a recurve bow, compound bow, crossbow, and so forth are manufactured in three primary pieces including a pair of limbs attached to a handle portion. The handle portion may further include risers. Each limb may be attached to a handle portion or riser and secured using a limb pocket or box. Each limb pocket may receive an end of each limb for engagement to the riser surface. Each limb is held in place within the limb pocket by a limb bolt which passes through a hole or slot in the end of the limb to engage a threaded bore in the engagement surface of the handle portion. Limb pockets may be integral to the limb portion or may be separate members which mutually engage the handle portion and a limb end. Through the use of a limb pocket, a limb may be connected to the riser at various pivot angles. By adjusting the pivot angle a shooter has the ability to vary the relative bowstring tension and draw force required to pull the bow string. As a result, the force imparted to the arrow for a given pull distance on the bow string may be varied.
Perhaps the greatest problem with adjusting the attachment angle, however, is the tendency of the bow limb to twist sideways or misalign relative to the bow riser when the bowstring is pulled and/or released. This tendency can profoundly disrupt a shooters aim and accuracy.
The problem may be particularly acute in the case of a compound bow. Compound bows differ in that a block and tackle mechanism is used to bend the bow which includes a pulley and wheel system attached at the free ends of the limbs to obtain a mechanical advantage in bending the bow. The limbs can be made stiffer than, for example a longbow of the same draw weight. Eccentrically mounted wheels enable one to use a much higher maximum draw weight because they provide a substantial reduction in the holding force of a drawn bow.
Thus, the combination of stiffer limbs and greater draw weight results in the application of large forces to the components of the compound bow. These forces can have a moment from the centerline of the bow and/or from the plane of a drawn bowstring. The forces from the bowstring and cables wound on the wheels may not align with the mounting of the limb to the handle because of the way the bowstring and cables are wound, or because of a sidewards force caused by a finger release or a sidewards force due to a cable guard. The result is a force tending to move the free ends of the limbs from side to side, i.e. laterally, when the bow is drawn and/or fired.
Thus, the structure for attaching the limbs to the handle must be substantial enough to resist these forces in order for the bow to perform consistently. Various devices and methods have been developed to address the aforementioned problems, and further which enable adjustment of the attachment angles between the bow limbs and the handle portion or riser while restraining the bow limbs from experiencing side to side or lateral motion relative to the riser.
Various devices have been developed to overcome the above aforementioned problems including the tendency of the bow limb to twist laterally relative to the riser. These devices include both those that are integral with the handle portion, as well as those which are separable from it. U.S. Pat. No. 4,261,320 ('320) describes a compound bow having its bow limbs seated in a pocket formed in the riser itself.
U.S. Pat. No. 5,231,970 ('970) describes and claims an archery bow limb construction which includes an archery bow limb adapted to be adjustably mounted to a planar mounting surface of an archery bow riser. The bow limb includes a top surface, a bottom surface, a proximate end and a distal end. A slot and an aperture extend from the top surface of the bow limb to the bottom surface. The slot extends laterally from the proximate end of the bow limb toward the distal end and terminates at the aperture. A fastener can extend through the aperture and the planar mounting surface and be threadably received in the bow riser to adjustably secure the bow limb to the bow riser.
The improvement relates to a bushing which is received in the aperture of the bow limb. The bushing includes a first hole and a key which is snugly received in the slot of the bow limb. The first hole extends vertically through the bushing and is adapted to receive the fastener. The bushing can comprise a body portion and a head portion, and the body portion can comprise the key. The body portion can comprise a cylinder which is received in the aperture of the bow limb. The bow limb construction can include a washer which has a bore extending through it, wherein the bore communicates with the first hole of the bushing and is adapted to receive the fastener.
U.S. Pat. No. 5,280,779 ('779) describes an archery bow provided with pivoting pocket members for attaching each limb to the bow handle. Each pocket has an upper recess for receiving and laterally supporting a limb, and pocket walls which extend away from the recess to straddle the sides of the handle.
U.S. Pat. No. 5,433,792 ('792) describes a compound archery bow having a handle which includes a laterally opening pocket, a nut received in the pocket and a screw extending through the limb into the pocket and received in the nut. In another embodiment, a first opening with a threaded insert is provided in the handle. A second threaded opening intersects the first opening. A screw extends through the limb into the first opening. A set screw is provided in the second opening to lock the limb screw. In another embodiment, the handle is provided with an opening that tapers toward the rear. A tapered bushing is received in the opening. A screw extends through a cable guide into the bushing to mount same. In another embodiment, a limb pivot arrangement is provided which includes a pair of concave channels on the handle, and complementary part-spherical bosses on the limb.
U.S. Pat. No. 5,507,270 describes a limb pocket with a plurality of plastic inserts located about the interior of the pocket for receiving the butt of a limb. The interior width of the pocket is greater than the width of the butt of the limb and the inserts reduce the interior width of the pocket to less than the width of the limb butt. The inserts are slightly tapered and slightly resilient to assure a close fit between the pocket and the limb. The end wall of the pocket optionally includes inserts for separating the end of the limb from the end wall of the pocket. The walls and floor of the pocket include shallow recesses for locating the inserts.
U.S. Pat. No. 6,024,076 describes an archery bow including pivoting limb pockets for attaching two split limbs or a single limb to the bow handle. The limb pockets are secured to the handle by an adjustment bolt. Circular mating portions on the pocket and handle permit rotation of the pocket about the handle. A slug which is press-fitted in the handle provides lateral stability between the pocket and the handle. The front wall of the pocket prevents limb movement in the axial direction and the top surface of the pocket limits upward movement.
U.S. Pat. No. 6,244,259 describes a bow limb mounting system for adjustably mounting a limb inner end of a bow limb to a riser mounting surface of a bow riser of an archery bow. The limb inner end pivots relative to the bow riser about a limb pivot axis. The pivot movement is produced by an adjustable strut assembly which varies an attachment angle between the limb inner end and the riser mounting surface, while restraining lateral movement between the two. The adjustable strut assembly has upper head and neck portions which connect to the limb inner end in a close tolerance manner, and an alignment block portion below the neck portion which is slidably and matingly seated in a cavity located below the mounting surface also in a close tolerance manner. A bolt extends through a central hole formed by the head, neck and alignment block portions and connects to a pivot pin, such that adjusting the bolt changes the distance between the limb inner end and the pivot pin to thereby change the attachment angle.
It would be advantageous to provide a mounting system for adjustably mounting a bow limb to a bow riser, wherein the bow limb is laterally restrained relative to the bow riser in an efficient yet solid manner. Furthermore, an adjustable bow mounting system which pivotally compensates the strut assembly at various attachment angles would provide greater structural stability under the typically high bowstring tensions. It is also notable that due to the variations in bowstring tension which result from adjustment of the attachment angle, it would be further advantageous to provide a mounting system which measures and indicates relative bowstring tension at the various attachment angles.
All US patents and applications all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety.